10xlinks

Since you asked about performance and SEO specifically, I would start with the boring basics before any design tweaks. Run the homepage and one product page through PageSpeed Insights on mobile, because the image weight on shops like this is usually the biggest cost. Convert the product photos to WebP, set real width and height on them, and lazy load everything below the fold. For SEO, make sure every product page has its own title and meta description written for a human, not just the product name repeated. Short descriptive text on category pages also helps a lot more than people expect. Also check that your canonical tags and sitemap only list pages you actually want indexed.